Parameters

Most Taffrail API endpoints accept request parameters. Send them as query parameters on a GET request or as a JSON body on a POST request.

Query parameters

On a GET request, query parameters control what the response includes. They are almost always optional.

Body parameters

Body parameters behave identically to query parameters — only the transport differs. See HTTP request methods.

User inputs and Variables

A Variable is a named parameter that powers a piece of advice. Variables can be passed in as input or produced by the Rules Engine from a formula, rule, or calculation.

Any request can include Variable name/value pairs as parameters:

/api/advice/{adviceSetId}?Tax_Year=2026

See Variables for the full reference.

Dotted Variable names

A Variable name can contain dots, as in Profile.Age. The naming rule spells out where they may appear. Send a dotted name whole, as one key, on every transport — in a query string:

/api/advice/{adviceSetId}?Profile.Age=42

or in a JSON body:

{ "Profile.Age": 42 }

A JSON body may nest the name instead: { "Profile": { "Age": 42 } } sets the same Variable. When a request carries both spellings, the flat Profile.Age key wins. The API follows a nested name through objects only. An array is always a value and never read by index, so { "Profile": [{ "Age": 42 }] } sets nothing.

Spelling matters: sending Profile_Age never sets Profile.Age. The response's variables[] lists the Variable as Profile.Age whether you sent it flat or nested.

Variable Dictionary

GET /api/dictionary returns every Variable available to your account. Each entry includes reservedName, dataType, validOptions, isClosedSet, and displayFormat.

Use this endpoint to discover which Variables a given integration can pass. Input parameters are not arbitrary — they must match Variables defined in your account. Pass a ruleSetId query parameter to scope the result to a single rule.

See the Variable Dictionary API Reference for the full schema.

Parameter reference

Parameter	Type	Required	Description
`adviceSetId`	String	Yes	The Advice Set identifier. Passed as a path parameter.
`filter`	String	No	Trim the `variables[]` array. See Filtering Variables in the response.
`fields[TYPE]`	String	No	Trim properties off each entry per type. See Sparse Fieldsets.
`{VariableName}`	Varies	No	Any Variable name/value pair. Look up valid names via the Variable Dictionary endpoint.

Sparse fieldsets

The API supports Sparse Fieldsets for trimming response payloads.